On 5/11/06, Christopher Montgomery <[EMAIL PROTECTED]> wrote:
On 5/10/06, David Brownell <[EMAIL PROTECTED]> wrote: > On Wednesday 10 May 2006 10:35 am, Christopher Montgomery wrote: > > In some > > ways it's easier to just stack requests into the full-speed frame and > > then plop the splits into whatever uFrame that happens to work out to, > > even if that means that, eg, an interval 1 iso request might be > > serviced in substantially different portions of the actual full-speed > > frame. > > So with interval 1 (one packet per frame), two consecutive packets > might go into uframes 7 then 0? That'd be more like interval 1/8, and > the next might be 15/8, and the next ... the notion was avoiding such > relatively non-isochronous behaviors.
[...]
Even if we restrict all the sitds of a given iso stream to be scheduled in the same uframe, they're not guaranteed to actually start in the same part of the uframe.. or even that uframe for that matter, the TT is free to delay actually starting the transfer for up to two additional uframes anyway.
I also forgot the example of OHCI, which appears to do some/all of the actual intraframe scheduling in hardware. Is it just sending out transaction packets in the order they're queued? (If so, the isos are occurring in totally random places in a given frame). Or something more complicated/opaque? The ohci driver balances the initial transaction scheduling amongst frames, but there's no rebalancing code (indeed if OHCI is doing frame scheduling in hardware, there'd be no need).The EHCI FS/LS sceduling should probably be aping the OHCI behavior as it's known to work well. I'll investigate this... unless someone would like to jump in with a simple answer that will save me the time :-) Monty ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid0709&bid&3057&dat1642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
